Plating machine



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PLATING MACHINE John V. Davis, Grosse Pointe Farms, Mich, assignor to The Udylite Corporation, Detroit, Mich, a corporation of Delaware Application August 24, 1955, Serial No. 530,223 29 Claims. (Cl. 134-58) This application is a continuation-in-part of my application Serial No. 397,506, filed December 11, 1953, now abandoned, bearing like title.

This invention relates to plating machines and more particularly to straight line automatic electroplating machines of the type in which a series of articles are conveyed on carriers through the machine from one end to the other and are removed from the carriers after being plated.

In conventional straight line automatic plating machines, the work carriers enter one end of the machine having a series of tanks which run the full length of the machine and the work travels from one tank to the next tank in an elevated position, and in the down position travels between rows of longitudinally disposed anodes to emerge from the plating bath at the opposite end of the machine. Such an arrangement permits only slight adjustments of the anodes to accommodate varied shaped parts in order to obtain uniform plating over the entire surface of the part. In the usual case where the part to be plated requires adjustment of the anodes, it is preferable and cheaper to plate the parts in a still tank with the parts disposed horizontally and the anodes disposed in nested relationship around the part even though it is necessary to move the plated parts by overhead hoists operated by a skilled plater.

It is an object of the present invention to provide a straight line plating machine of an improved nature which eliminates the disadvantages of previous devices of this type and results in a substantial saving of time and space when plating a plurality of workpieces simultaneously.

It is another object to provide an improved plating machine of the above nature in which means are provided for selectively lifting one or more of a plurality of workpieces from the plating bath, and allowing the workpieces which have not been fully plated to remain continuously in the plating bath until their removal time has arrived.

It is a further object to provide a plating machine of the above nature in which the fully plated workpieces are skip transferred, that is, selectively and automatically removed from the plating station in any desired sequence, regardless of their relative longitudinal position in the plating station, and in which unplated workpieces are automatically transferred to those positions in the plating station vacated by plated parts.

it is also an object to provide a plating machine of the above nature in which the number and size of plating tanks, workpiece capacity, sequence of removal and plating time may be varied to suit individual requirements.

It is another object to provide a plating machine of the above character in which novel means are provided for preventing an unplated workpiece from stopping in a plating section which is unable to receive the workpiece, and which automatically halts the forward movement of a workpiece which has reached its proper position on the transfer track,

" nited States Patent ice It is a further object to provide a plating machine of the above type, which is provided with a transfer track having displaceable sections, and in which the means for lifting and lowering the workpiece with respect to the plating bath operates to displace the displaceable section of the transfer track directly thereabove, thereby providing a simple and efiicient mechanism for effecting skip transfer of the articles being plated.

It is a further object of this invention to permit any one or more of a plurality of cells or tanks at a liquid treating station to be selectively bypassed, to facilitate inspection, cleaning and repair thereof, without interruption of the operation of the other elements of the machine and without interruption of the continuous processing of workpieces by the machine.

Other objects, features, and advantages of the present invention will become apparent from the subsequent description, taken in conjunction with the accompanying drawings.

In the drawings:

Figure 1 is a perspective view of a straight line plating machine with the tanks removed having included therein the principles of the present invention and showing the general location of the novel plating station with respect to the other portions of the machine;

Figure 2 is a perspective view of the plating station with the frame down and showing the cam shaft and cam drive mechanism for the movable track sections;

Figure 3 is a perspective view similar to Figure 2 but with the frame in the raised position and with one of the movable track sections (34a) held inwardly so as to displace the transfer track section directly thereabove,

and to form a continuous track;

Figure 4 is a perspective view of the interior of the transfer track of station 29, showing the movable track sections thereof with the selecting station in contact with a carrier in its lowered position;

Figure 5 is a fragmentary cross-sectional view taken along the line 55 of Fig. 2 and showing the cooperation of a track selector cam and a movable track support as well as the manner in which a movable track section engages a carrier; this figure also shows a first embodiment of a pivotally mounted transfer track displaceable section which is disposed directly above the movable track section of station 29;

Figure 6 is a fragmentary cross sectional view similar to the upper portion of Figure 5 but showing the selected movable track section in its raised position with the displaceable section of the transfer track directly thereabove' being pivoted upwardly to allow the movable track section to be aligned with and become a part of the transfer track;

Figure 7 is a fragmentary sectional view taken along the line 77 of Fig. 5 showing a means for pivotally mounting the transfer track displaceable sections above station 29;

:Figure 8 is a fragmentary cross-sectional view similar to Fig. 5 but showing a second embodiment of a displaceable transfer track section disposed above station 29;

Figure 9 is a fragmentary cross-sectional view similar to the upper portion of Fig. 8 but showing the selected movable track section in its raised position with the displaceable section of the transfer track directly thereabove being slid upwardly to allow the movable track section to be aligned with and become a part of the transfer track above station 29;

Figure 10 is a fragmentary sectional view taken along the line 10-40 of Figure 8 showing a means for slidably mounting the transfer track displaceable sections above station 29; 1

Figure 11 is a perspective view of a pusher retractor guide with its gate in the open position to allow a pusher to fall behind a carrier;

Figure 12 is a perspective view similar to Figure 11 but with the gate in the closed position to maintain the retracted position of the pusher;

Figure 13 is a fragmentary elevational view taken along the line IL -13 of Figure 2 and showing the operating means for the pusher retractor gate;

Figure 14 is a fragmentary cross-sectional view taken along the line 14-44 of Figure 3 showing the pusher slides and their attendant mechanism;

Figure 15 is a schematic view showing the relation between the various stations and tanks, the pretreating and rinsing stations being shown in their lowered positions and the plating station in its upper position;

Figure 16 is a schematic view similar to Figure 15 I but with a workpiece moved from the plating station to t the rinse standby station and a new workpiece replacing the previous one in the plating station;

Figure 17 is a schematic view similar to Figures 15 and 16 but with the pretreating and rinse stations in their raised positions and the plating station in its lowered position;

Figure 18 is a schematic view similar to Figures 15 to 17 but with the plating station again raised with another finished workpiece;

Figure 19 is a schematic view showing the pusher slides and their cooperation with a pusher retracting guide, a first pusher being shown in its engaging position;

7 Figure 20 is a schematic view similar to Figure 19 but with the carrier raised to the upper position;

Figure 21 is a schematic view similar to Figure 19 but with the carrier advanced by the first pusher;

Figure 22 is a schematic view similar to Figures 19 and 20 but with a new carrier in plating position;

Figure 23 is a side elevation view of the apparatus of this invention, partly schematic, illustrating a chain pusher means for transferring a selected carrier along the transfer track to another portion of the machine, and for tansferring another carrier to the position vacated by the previously removed carrier; 3

Figue 24 is a functional representation of the physical relationship between the movable elements of the apparatus of Fig. 23, and adjacent stations, and the limit switches which control, in part, the several movements of those elements;

Figure 25 is a functional representation of the physical relationship between certain cam operated switches and earns mounted upon the cam shaft 63 of Figure 2 which control, in part, the energization of the cam motor 63 of Figure 2 and the chain of Figure 23;

Figure 26 is a schematic representation of a portion of a suitable electrical system for controlling the operation of the apparatus of this invention when the chain-type of horizontal transfer means is employed;

Figure 27 is a schematic representation of the remaining portion of the electrical system represented in Figure 26, and should be placed below Figure 26 for proper orientation;

Figure 28 is a functional representation of a cam, modified in form from the cam of Figure 25, and the switches actuated thereby for permitting the selective bypassing of any one of the tanks of Figures 23 or 24;

Figure 29 is a partial schematic representation of a manner of changing the circuits of Figure 26 to utilize the cam actuated switches of Figure 28 of the drawings;

Figure 30 is a partial schematic representation of a manner of changing the circuits of Figure 27 to coordinate the one-cell shift operation with the bypassing arrangements of Figures 28 and 29; and

Figure 31 is a fragmentary, partially cut-away perspective view or" one plating cell with its anode nest and with a Work carrier in position thereover.

The present invention provides automatic apparatus which allows a rack of parts to remain at rest in a cell of the plating tank provided with a nest of conforming anodes for the time period required to produce the required deposit, and concurrently enables the most efficient utilization of preliminary tanks, such as cleaning and rinsing tanks, which require much shorter dwell periods of the part being plated than the plating cells. In general, this automatic cycle is accomplished by a plating station which is provided with means for selecting in sequence empty plating cells to accommodate work carriers as they emerge from the preliminary tanks, as is more fully described hereinbelow.

The general arrangement and operation of the straight line plating machine embodying the present invention is perhaps best seen in schematic Figures 15 through 18. The machine includes a plurality of treatment tanks, three such tanks being shown in the present embodiment, namely a pretreatment tank 21, a plating tank 22 and a rinse tank 23. Plating tank 22, which is schematically indicated in Figures 15 through 18 is in the actual apparatus of this invention a segmented tank, the plurality of segments forming plating station 29 of Figure 1. In each of the segments of tank 22, the anodes are hung across the width of the machine in nests which conform to the shape of the part being plated, and it will be apparent that continuous forward travel through these tanks is impossible. It will be understood that the nature, number and capacity of the tanks could be varied from those shown and that the principles of the invention could be applied to other than the illustrated sequence of operations. The workpieces 24 are held by carriers 25 during their movement through the machine and into and out of the various tanks. These carriers travel along a pair of transfer tracks each of which extends the length of the machine and is made up of sections corresponding to the stations of the machine. Since the sequence of movement of the carriers is important in understanding the operation of the invention, each carrier in Figures 15 through 18 is given a separate reference numeral. Thus, in the figures, carriers 25a to 25m are marked.

Section 22' of the plating tank 22, with a representative anode nest and with a carrier 25 in position thereover, is illustrated in Figure 31 of the drawings. In that view the work carrier 25, including its rollers 61, is disposed over tank 22' and supports a pair of hangers and 172 which have suitably conformed projections to support a plurality of workpieces 24-, those workpieces representatively being shown to be automobile bumpers.

Anodes 174 are hung or otherwise supported upon anode bars 176 which are disposed rectangularly or octagonally so that the anodes 174 define a nest into which the workpieces 24 may be moved. Anode bars 176 are supported upon tank section 22' by means of support elements 178, either the elements 178 or the tank section 22, or both, being of insulating material. Electrical connection is made to the anode bars 176 and hence to the anodes 174 by means of anode terminals 180. Pairs of spring arms 182 and 184 are disposed at opposite sides of the tank section 22' and in position to engage contact pads 186 and 188, respectively, which are electrically integral with the work carrier 25 and hence with the workpieces 24. Appropriate electrical connection is made to the pairs of arms 182 and 184 so that the workpieces 24 serve as the cathode of the electrolytic cell. In view of the use of anode nests, each of which is defined by a plurality of anodes, such as anodes 174, supported upon anode bars, such as anode bars 176, the workpieces must be moved into and out of the individual nests in a vertical sense.

The stations of the illustrated straight line plating machine include a loading station 26, pretreatment station 27, a transfer and drain station 28, a plating station 29, a rinse transfer station 31, a rinse station 32 and an unloading station 33. The workpieces on their carriers move in succession from station 26 to station 33, and as the workpieces reach tanks 21, 22 and 23 they are lowered into these tanks for appropriate treatment. For this purpose, the transfer track sections above each tank are movable in a vertical direction so that the carriers disposed on such vertically movable sections can be lowered. As will be seen later, the portion of the transfer track above plating tank 22 includes means for selectively removing and replacing one or more workpieces from a group which are being plated. It may be stated here briefly, for purposes of describing the general operation of the machine, that the movable transfer track sections in station 29 comprise a plurality of relatively movable track sections 34a, 34b, 34c, and 34d, and that means are provided for causing these track sections to selectively engage one or more carriers 25 when station 29 is in its lower position, so that those carriers 25 not engaged by their respective track sections remain in the plating tank when the track sections of station 29 are raised.

In describing the sequence of operations of the straight line plating machine embodying this invention, we start with an initial condition in which track 35 of station 27 and track 36 of station 32 are in their lower positions, whereas track sections 34 of station 29 are in their upper positions. At this time the workpieces held by carriers 25b, c, d are being pretreated and the workpiece held by carrier 25 is being rinsed. Track section 34a of station 29 has just lifted carrier 25 during its upward movement, but carriers 25g, h, i have remained in their lower positions within plating tank 22. Carrier 25:: is on track 37 of plating transfer station 28, ready to be transferred to track section 34a to replace carrier 25 Carrier 25a on track 38 of loading station 26 has just received a workpiece, whereas carrier 25k on track 39 of unloading station 33 has just been relieved of its finished workpiece.

The carrier transfer mechanism (described in detail below) now operates to shift carrier 25 past carriers 25g, h, i to track 40 of rinse transfer station 31 and to shift carrier 25e into place on track section 340:, as shown in Figure 16. This means of course that the workpiece held by carrier 25e may now take the position in plating tank 22 which was vacated by carrier 25], the latter being held in readiness for rinsing in tank 23. Meanwhile, carrier 25a has been transferred to the first portion of track 35 in station 27 which extends rearwardly from tank 21. Track 39 of unloading station 33 has been elevated to permit its carrier 25k to be returned by a pair of overhead return tracks (not shown in the schematic drawings).

Track sections 34 of plating station 29 are then lowered, placing carrier 252 into the plating tank as shown in Figure 17. At the same time, tracks 35 and 36 of stations 27 and 32 respectively are raised. The transfer mechanism now operates to shift carrier 25d from track 35 onto track 37 of plating transfer station 28, and to move carriers 25a,

b, c forwardly on track 35, carrier 25a moving into position above pretreatment tank 21. Track 38 is simultaneously elevated intoalignment with the overhead return track (not shown) to receive a new carrier 25m. At the same time, carrier 25f is moved from rinse transfer station 31 onto track 36 of rinse station 32, carrier 25 which had been in the rinse tank being shifted onto descended track 39 of unloading station 33.

When another workpiece has been completely plated, for example the workpiece held by carrier 251', this workpiece is removed from plating tank 22 by its appropriate track section 34d. This is shown in Figure 18, wherein it will be noted that tracks 35 and 36 are again lowered and track sections 34 raised, as in Figure 15. It is thus seen that due to the novel arrangement of the movable track sections in plating station 29, the workpieces in plating tank 22 are selectively removed, the sections of the transfer track serving as the selecting means. Carrier 251' will now be shifted to track 40 of rinse transfer station 31 and carrier 25d will be shifted from plating transfer station 28 into position on track section 34d. Meanwhile, track 38 of loading station 26 has been lowered to receive a new workpiece on carrier 25m and the workpiece on carrier 25 has been removed at unloading station 33.

The cycle will continue as before, with the workpieces in plating tank 22 being removed in any desired sequence. Referring now more particularly to the construction of Figures 1-14, Figure 1 shows the general arrangement of the machine, and includes loading station 26, pretreating station 27, plating transfer station 28, plating station 29, rinse transfer station 31, rinse station 32, and unloading station 33. The construction of portions of the machine is generally similar to that shown in patent to Davis No. 2,484,079 for Hydraulically Operated Plating Machine, and certain parts of the present machine not relating to the present invention therefore need not be described in detail. Loading station 26 includes an elevator frame 41 which can be lifted by actuating chains 42 so that tracks 38 of the loading station may be aligned with overhead carrier return tracks 43. When in its lowered position tracks 38 of the elevator frame are aligned with tracks 35 of pretreatment frame 44 at pretreatment station 27. The latter frame is also vertically movable by means of a plurality of chains as 45, and when in their upper position tracks 35 of pretreatment frame 44 are aligned with tracks 37 of plating transfer station 28. Pusher means, preferably in the form of reciprocating pusher slides, described later, are provided for transferring carriers 25 from elevator fame 41 to pretreatment frame 44 and from the pretreatment frame to station 28. The means for vertically moving the loading and unloading elevators, and pretreatment frame, as well as the actuators for the carrier pusher means, forming in themselves no part of the present invention, need not be described in detail, but reference is here made to the above mentioned Patent No. 2,484,079 wherein such means are described. It may be here stated, however, that reference is hereinafter made to the pusher mechanism as it affects the transfer of carriers from plating transfer station 28 to plating section 29 and from the plating section to rinse transfer station 32.

The general construction of plating station 29 is best seen in Figures 2 and 3. The station includes a vertically movable frame generally indicated at 46 which has a pair of upper longitudinal members 47, a pair of lower longitudinal members 48, and vertical members 49. The frame carries a plurality of rollers 51 by means of which the entire frame is vertically movable, rollers 51 being guided by a plurality of vertical stationary rails 52. The means for lifting and lowering the frame preferably comprises a plurality of chains 53 on both sides of the machine, these chains being operable by a hydraulic cylinder 54 visible in Figure 1, together with linkage similar to that for elevating pretreatment frame 44.

As indicated previously, plating frame 46 includes means for selectively lifting one or more of a plurality of carriers resting on the plating tank, and this means includes a plurality of pairs of movable track sections 34. As is best seen in Figures 2 and 4, track sections 34 are disposed inwardly of upper longitudinal frame members 47, and are each pivotally supported by a pair of pivoted arms 55. Each of these arms is pivoted by a pin 56 to a pair of lugs 57 secured to lower longitudinal members 48, so that arms 55 are movable between an outer position as shown by the central and right hand pairs of arms in Figures 2 and 4 and an inner position as shown by the left hand pair of arms in Figures 2 and 4. Sufiicient lateral space is of course allowed between track sections 34 and longitudinal frame members 47 to permit this swinging movement.

When any selected set of arms 55 is swung to the inner position, with frame 46 in its upper position, the track sections 34 carried by such arms 55 will be in alignment with tracks 37 of station 28 and with tracks 40 of station 31. In order to allow a carrier 25 to be moved from the frame 46 when such frame is in its upper position a displaceable track section, as 10, is suitably disposed in alignment with the transfer track directly above each movable track section 34. The displaceable track sections 10 are preferably either pivotally or slidably mount- 

